LONGMONT -- A 12-year Longmont police veteran was arrested Wednesday in Larimer County on suspicion of felony sexual assault.

Officer Chris Martinchick, 43, was placed on paid administrative leave from his police duties on July 3 after Larimer County investigators informed police officials that Martinchick was under investigation. He turned himself in at the Larimer County Jail on Wednesday on a warrant for two counts of felony sexual assault and two counts of misdemeanor invasion of privacy for sexual gratification, according to police.

Longmont police report that the incident happened while Martinchick was off duty in Loveland and involved a woman he knew there.

According to an arrest warrant affidavit for Martinchick, the woman called the sheriff's office on July 2 to report that she believed Martinchick assaulted her while she was asleep after taking Nyquil and a prescription muscle relaxant March 30. She said she had gone to bed wearing only undergarments and that Martinchick was in bed with her. The next morning she woke and felt vaginal pain, according to the warrant.

She told investigators that she confronted Martinchick and he said he had sex with her but did not finish because he felt bad that she was asleep. She reported that she did not feel he needed further confrontation at the time. She said that about 10 days later she took the prescription muscle relaxant again and went to sleep. She woke to bright flashes in the room and discovered Martinchick taking photos with his cell phone's camera and found she was no longer wearing undergarments.

The woman made a call to Martinchick on July 2 under the supervision of investigators during which he reportedly acknowledged the unwanted contact and photos and mentioned that he was receiving treatment for sexual addiction, according to the affidavit.

Larimer County investigators served a search warrant on Martinchick on July 3 and seized is phone and laptop, according to his arrest warrant affidavit. Investigators reportedly recovered 22 graphic photos of a woman's genitals. The woman who reported the assault confirmed to investigators that the photos were of her, that they were apparently taken while she was sleeping, and that she did not consent to the photography. The phone's memory card showed the photos were taken Feb. 14 and April 21.

The Longmont police also have launched an internal investigation. Martinchick will remain employed while the internal investigation is completed.

Longmont Deputy Chief Craig Earhart said the department is "disappointed and embarrassed" that an officer was arrested on suspicion of such serious charges.

"The Longmont police service takes pride in the service we provide to the public and hold sacred the trust that our community places with our department and our officers," he said, reading from a prepared statement. "This type of conduct, if proven to be true, is unacceptable under our code of conduct, and will be dealt with in an appropriate manner when a disposition in this matter is reached. Be assured that the Longmont Police Service has and will continue to fully cooperate in the criminal investigation."

Martinchick has been assigned to the traffic unit for the past five years, according to Longmont police.

Martinchick also was arrested in 2009 on suspicion of driving while ability impaired. He pleaded guilty to careless driving later in the year. Earhart said he did not have the details about that arrest, but he said Martinchick was disciplined.

He is scheduled for an advisement hearing in Larimer County Court at 1:30 p.m. today.